1. Field of the Invention
The present invention relates to an engine in which a first camshaft having a power input portion at one end thereof and a second camshaft interlocked and connected with the first camshaft at one end portion thereof have axes which are parallel with each other and are rotatably supported on a cylinder head and in which a driven gear meshing with a drive gear provided at the other end portion of one of the first and second camshafts is provided on an auxiliary device drive shaft connecting to an auxiliary device mounted on an engine main body including the cylinder head.
The present invention relates an engine in which first and second camshafts having axes which are parallel with each other along a cylinder arrangement direction are rotatably supported by pluralities of first and second bearing portions, respectively, which are provided for the respective camshafts on a cylinder head at positions spaced apart from each other in the cylinder arrangement direction, in which first and second rotational wheels which are interlocked and connected with each other are fixed to the first and second camshafts, respectively, at portions which protrude from the one endmost first and second bearing portions of the pluralities of the first and second bearing portions which are disposed at one end of the cylinder head along the cylinder arrangement direction, and in which a cylindrical protruding portion which protrudes further towards the one endmost bearing portion than the second rotational wheel is provided on the first rotational wheel.
2. Description of the Related Art
An engine is known in, for example, JP-A-8-261001 in which a drive gear provided on a camshaft is caused to mesh with a driven gear provided on an auxiliary device drive shaft which connects to a vacuum pump and a hydraulic pump.
Conventionally, an engine as described above is known in, for example, JP-A-3-117603.
The known conventional engine is a single overhead camshaft (SOHC) engine having a single camshaft. However, in attempting to apply an auxiliary device driving mechanism similar to the above conventional one to an engine having a pair of camshafts, a construction is desired to be provided which can drive auxiliary devices in such a manner as to make the engine as compact in size as possible while avoiding the interference of the auxiliary device driving mechanism with the pair of camshafts.
In the engine, in a case where the first rotational wheel fixed to the first camshaft at the position adjacent to the one endmost first bearing portion disposed at the one end of the cylinder head along the cylinder arrangement direction of the plurality of first bearing portions provided on the cylinder head at the positions spaced apart from each other in the cylinder arrangement direction has the cylindrical protruding portion which protrudes further towards the one endmost bearing portion than the second rotational wheel, in the event that the one endmost first bearing portion which rotatably supports the first camshaft and the one endmost second bearing portion which rotatably supports the second camshaft are set at the same position in a direction directed along the axes of the two camshafts, a space between the first and second rotational wheels and the one end of the cylinder head becomes large due to the first rotational wheel having the protruding portion, and this calls for the enlargement of the engine.